U.S. patent application number 10/096363 was filed with the patent office on 2002-11-21 for method and device for controlling a drive-line including a cvt.
Invention is credited to Braun, Steffen, Piepenbrink, Andreas, Sommer, Stefan.
Application Number | 20020173390 10/096363 |
Document ID | / |
Family ID | 7677150 |
Filed Date | 2002-11-21 |
United States Patent
Application |
20020173390 |
Kind Code |
A1 |
Sommer, Stefan ; et
al. |
November 21, 2002 |
Method and device for controlling a drive-line including a CVT
Abstract
The invention describes a method and a device for controlling a
drive train of a motor vehicle with a drive assembly and a
continuously variable automatic transmission with a variable speed
gear, wherein an electronic control unit for controlling at least
the continuously variable automatic transmission and an emergency
device are provided, with this unit being activated in the event of
failure of the electronic control unit and a constant
pressure/force ratio being established in the variable speed gear.
Pursuant to the invention, in the event of failure of the
electronic control unit the frictional connection between the drive
assembly and the continuously variable automatic transmission is
interrupted before the emergency driving mode is made available
through the emergency device by re-establishing the frictional
connection.
Inventors: |
Sommer, Stefan; (Saulgau,
DE) ; Piepenbrink, Andreas; (Grunwald, DE) ;
Braun, Steffen; (Langenargen, DE) |
Correspondence
Address: |
DAVIS & BUJOLD, P.L.L.C.
500 NORTH COMMERCIAL STREET
FOURTH FLOOR
MANCHESTER
NH
03101
US
|
Family ID: |
7677150 |
Appl. No.: |
10/096363 |
Filed: |
March 12, 2002 |
Current U.S.
Class: |
474/18 ;
474/28 |
Current CPC
Class: |
F16H 61/66254 20130101;
F16H 61/12 20130101; F16H 61/66272 20130101 |
Class at
Publication: |
474/18 ;
474/28 |
International
Class: |
F16H 059/00; F16H
063/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 13, 2001 |
DE |
101 11 830.9 |
Claims
1. Method for controlling a drive train of a motor vehicle with a
drive assembly (1) and a continuously variable automatic
transmission (3) with a variable speed gear (V), wherein an
electronic control unit (15) for controlling at least the
continuously variable automatic transmission (3) and an emergency
device are provided, with this unit being activated in the event of
failure of the electronic control unit (15) and a constant
pressure/force ratio being established in the variable speed gear,
characterized by the fact that in the event of failure of the
electronic control unit (15) the frictional connection between the
drive assembly (1) and the continuously variable automatic
transmission (3) is interrupted before the emergency driving mode
is made available through the emergency device by re-establishing
the frictional connection.
2. Method pursuant to claim 1, characterized by the fact that the
frictional connection between the drive assembly (1) and the
continuously variable automatic transmission (3) is re-established
after re-starting the drive assembly (1) in the event of a failed
electronic control unit (15).
3. Method pursuant to claim 1 or 2, characterized by the fact that
after re-starting the drive assembly (1) the frictional connection
is re-established at a gear ratio (INOT) which is predefined so as
to make sufficient power for starting to move the vehicle and a
maximum vehicle speed of at least 100 km/h is made available,
wherein for the emergency driving mode preferably a gear ratio in
the range of 1.0 to 1.6, particularly preferably in the range of
1.3 to 1.6 is set.
4. Method pursuant to one of the claims 1 through 3, characterized
by the fact that for the interruption of the frictional connection
between the drive assembly (1) and the continuously variable
automatic transmission (3) a valve (44), which is arranged in a
pressure feed line (45) to a clutch arrangement of a
forward/backward driving unit (9), can be switched through an
emergency program pressure (PNOT) into a position that interrupts
the pressurizing medium flow to the clutch arrangement.
5. Method pursuant to claim 4, characterized by the fact that the
valve (44), which is arranged in the pressure feed line (45) to the
clutch arrangement of the forward/backward driving unit (9), is
switched through an emergency program pressure (PNOT) and a
magnetic device (60), which is activated in the event of failure of
the electronic control unit (15) and acts against the force of a
main pressure, into a position that releases the pressurizing
medium flow to the clutch arrangement so as to re-establish the
frictional connection after re-starting the drive assembly (1).
6. Device for controlling a drive train of a motor vehicle,
particularly pursuant to one of the claims 1 through 5, which
contains a drive assembly (1), a continuously variable automatic
transmission (3) with a variable speed gear (V), an electronic
control unit (15) for controlling at least the continuously
variable automatic transmission (3) and an emergency device, which
is activated in the event of failure of the electronic control unit
(15), characterized by the fact that in a pressure feed line (45)
to a clutch arrangement of a forward/backward driving unit (9) of
the continuously variable automatic transmission (9) a valve (44)
is arranged, which is switched through an emergency program
pressure (PNOT) into a position that interrupts the pressurizing
medium flow to the clutch arrangement in the event of failure of
the electronic control unit (15) so as to interrupt the frictional
connection between the drive assembly (1) and the continuously
variable automatic transmission (3).
7. Device pursuant to claim 6, characterized by the fact that the
valve (44) is switched into a position that releases the
pressurizing medium flow to the clutch arrangement when re-starting
the drive assembly (1) and in the event of a failed electronic
control unit (15).
8. Device pursuant to claim 6 or 7, characterized by the fact that
the valve (44) is selected in dependency upon the emergency program
pressure (PNOT), a pressure (PKV) in the pressure feed line (45) to
the clutch arrangement of the forward/backward driving unit (9), a
main pressure (PDH) and a pressure control pressure (PEDS).
9. Device pursuant to one of the claims 6 through 8, characterized
by the fact that the valve (44) includes a first valve stem (46)
and a second valve stem (47), wherein the first valve stem (46)
assumes a position that releases or blocks the pressure feed line
(45) to the clutch arrangement and the second valve stem (47),
whose working area (50) is connected with the working area (48) of
the first valve stem (46) via a line (49), establishes the
switching position of the first valve stem (46).
10. Device pursuant to claim 9, characterized by the fact that the
first valve stem (46) is designed with a first piston section (51)
and a second piston section (53), which is separated from the first
one by an area (52) of smaller diameter, wherein an effective area
(51A) of the first piston section (51) facing away from the second
piston section (53) limits the pressure feed line (45) to the
clutch arrangement while acting against a spring (54), and a
stepped effective surface (53A), which faces away from the first
piston section (51), of the second piston section (53) limits a
chamber (48A) with a connection (55) for the emergency program
pressure (PNOT) in the working area (48) of the first valve stem
(46), wherein the line (49) to the working area (50) of the second
valve stem (47) joins into a gap (48B) between these first and
second piston sections when the first valve stem (46) assumes a
position that releases the pressure feed line (45).
11. Device pursuant to claim 9 or 10, characterized by the fact
that the second valve stem (47) is designed with a first piston
section (56) and a second piston section (58), which is separated
from the first one by an area (57) of smaller diameter, wherein an
effective area (56A) of the first piston section (56) facing away
from the second piston section (58) limits, while acting against a
spring (57), a chamber (50A), into which a connection (58) for the
emergency program pressure (PNOT) and the line (49) to the working
area (48) of the first valve stem (46) join, which both can be
blocked by the first piston section (56); that a smaller effective
area (58A) of the second piston section (58), which is facing away
from the first piston section (56), in the working area (50) of the
second valve stem (47) limits a chamber (50B) with a connection
(59) for the main pressure (PHD) and a magnetic device (60), which
is activated in the emergency program; and that a connection (61)
for the pressure control pressure (PEDS) joins into a gap
(50C).
12. Device pursuant to one of the claims 9 through 11,
characterized by the fact that during the normal operating mode the
first valve stem (46) assumes a first position (POSI), in which it
is switched to a mode that releases the pressure feed line (45) to
the clutch arrangement against the pressure (PKV) in the pressure
feed line (45) to the clutch arrangement and against spring
elasticity, and the second valve stem (47) assumes a first position
(POSIII), in which it blocks the connection (58) for the emergency
program pressure (PNOT) and the line (49) to the working area (4)
of the first valve stem (48) when the main pressure (PHD) and the
pressure control pressure (PEDS) are applied.
13. Device pursuant to one of the claims 9 through 12,
characterized by the fact that in the event of failure of the
electronic control unit (15) the first valve stem (46) is switched
through the emergency program pressure (PNOT) into a second
position (POSIII), in which it blocks the pressure feed line (45)
to the clutch arrangement with its first piston section (51) and
the connection to the line (49) that leads to the working area (50)
of the second valve stem (47) with its second piston section (53),
and in which the second valve stem (47) remains in its first
position (POSIII) as long as the main pressure (PHD) is applied to
it.
14. Device pursuant to one of the claims 9 through 13,
characterized by the fact that when re-starting the drive assembly
(1) and in the event of a failure of the electronic control unit
(15) the first valve stem (46) is switched into its first position
(POSI), in which its first piston section (51) releases the
pressure feed line (45) to the clutch arrangement and the
connection to the line (49) that leads to the working area (50) of
the second valve stem (47), while the second valve stem (47) is
switched through the magnetic device (60) into a second position
(POSIV), in which its first piston section (56) releases the
connection (58) for the emergency program pressure (PNOT) and the
connection of the line (49) that leads to the working area (48) of
the first valve stem (46).
15. Device pursuant to one of the claims 6 through 14,
characterized by the fact that the emergency driving device in the
variable speed gear (V), which contains a first taper disk set (10)
on a drive shaft and a second taper disk set (12), which is
connected with the first set through a belt-wrap device (11), on a
driven shaft (13), wherein the first taper disk set (10) consists
of an axially fixed taper disk and an axially displaceable primary
disk (S1) with a setting area (41) and the second taper disk set
(12) consists of an axially fixed taper disk and an axially
displaceable secondary disk (S2) with a setting area (42), adjusts
the constant pressure/force ratio between the primary disk (S1) and
the secondary disk (S2) through positioning elements, wherein the
pressure level of the setting area (42) of the secondary disk (S2)
is constant.
16. Device pursuant to claim 15, characterized by the fact that the
positioning elements are a primary valve (38) and a secondary valve
(39), which are pre-controlled via a first and a second emergency
valve (30, 31), wherein preferably an electromagnetic pressure
control valve (27) has a pre-controlling effect on the first and
second emergency valves (30, 31).
17. Device pursuant to claim 15 or 16, characterized by the fact
that a pump (22) is followed by a first and a second pressure
reduction valve (24, 25) (lines 23A, 23B), a first and second
electromagnetic pressure control valve (27, 28) are connected with
the first pressure control valve (24) (line 26), the first
electromagnetic pressure control valve (27) is connected with a
first and second emergency valve (30, 31) (lines 29, 29A, 29B), the
first emergency valve (30) is connected with a primary valve (38)
(lines 34 and 35), the second emergency valve (31) is connected
with a secondary valve (39) (lines 36 and 37), the primary valve
(38) as well as the secondary valve (39) are connected with the
pump (22) (lines 23, 23C, 23D, 23F), that this way the pressure
level for the setting area (42) of the secondary disk (S2) is
determined via the secondary valve (39) (line 23E), the primary
valve (38) determines the pressure level of the setting area (41)
of the primary disk (S1) (line 43), the second pressure reduction
valve (25) is connected with the two emergency valves (30, 31)
(lines 32 and 32A), the switching positions of the first and second
emergency valve (30, 31) are determined by the first
electromagnetic pressure control valve (27) so that in a first
position B of the two emergency valves (30, 31) the first pressure
control valve (27) has a pre-controlling effect on the primary
valve (38) and the second pressure control valve (28) has a
pre-controlling effect on the secondary valve (39) (lines 29, 29B,
35 and/or 33, 37), that in a second position A of the two emergency
valves (30, 31) the pressure level of the second pressure reduction
valve (25) has a pre-controlling effect both on the primary valve
(38) and on the secondary valve (39).
Description
[0001] The invention relates to a method and a device for
controlling a drive train of a motor vehicle having a drive
assembly and a continuously variable automatic transmission
pursuant to the kind described more closely in the generic
description of patent claim 1 or 6.
[0002] In modern motor vehicles familiar electronic control units,
such as electronic transmission controls which can also be
connected with electronic engine controls, are used for controlling
the drive train.
[0003] Such electronic control units are also required for a
continuously variable automatic transmission, which is also called
a CVT (continuously variable transmission) automatic transmission,
which contains a variable speed gear with a first taper disk set on
a drive shaft as the primary disk set and with a second taper disk
set on a driven shaft as the secondary disk set. Each taper disk
set respectively consists of an axially fixed first disk and an
axially displacable second disk which are described as a primary
disk or as a secondary disk, depending on whether they are assigned
to the primary disk set or secondary disk set. In order to be able
to adjust the primary disk or the secondary disk, they are fed a
pressurizing medium wherein the pressure that is respectively
applied to the setting spaces of the primary disk and the secondary
disk is determined, via an electronic control unit and
electromagnetic positioning elements and hydraulic valves that are
selected by this control unit.
[0004] In case of a malfunction of the electronic control unit,
emergency programs are generally provided which are designed so as
to be able to operate a vehicle in an emergency operating mode.
[0005] From EP 0 784 767 B1, we know of an emergency device for
controlling a CVT wherein an electronic control device determines
the pressure level of the particularly dynamically unbalanced
setting spaces of the primary disk and the secondary disk via the
electromagnetic positioning elements and the hydraulic valves. The
emergency device, which is provided in the event of failure of the
electronic control device, contains two pressure control valves,
two pressure reduction valves and at least one emergency valve,
wherein a primary valve and a secondary valve adjust a constant
static pressure ratio and/or force ratio between the primary disk
and the secondary disk with a constant static secondary pressure
level.
[0006] The amount of these static force ratios and of the dynamic
forces that are applied to the dynamically pressure non-compensated
disks allows a determination as to how great the gear ratio change
of the CVT is when transitioning from normal operation to the
emergency operating mode. The emergency operating mode is described
as a state of the CVT in which the governing speed and applied
pressure control of the secondary disk are interrupted.
[0007] The problem with these hydraulic emergency programs lies in
the control of the unavoidable hydraulic valve tolerances because a
shift in the constant pressure ratio directly affects the gear
ratio setting range.
[0008] From experiments we know that pressure tolerances of 5 bar
can be present on the variable speed gear disks. The appropriate
gear ratios in the emergency program are dispersed accordingly. For
example, in the case of a tolerance setting with minimal pressure
on the primary disk and maximum pressure on the secondary disk
within the tolerance range, the gear ratio can be too far towards
the smallest possible gear ratio (LOW) with a value considerably
above 1, which drastically limits the permissible maximum speed
during the emergency operating mode and wherein an abrupt change
from a normal mode, at high speed, into the emergency operating
mode can lead to a so-called over speeding of the driving motor,
transmission damage and possibly a destruction of the
transmission.
[0009] When considering a tolerance setting where a maximum
pressure exists on the primary disk and a minimum pressure on the
secondary disk within the tolerance range, a mean gear ratio level
arises with a gear ratio in the direction of the largest possible
gear ratio (overdrive, OD). A transition from the normal driving
mode with a high vehicle speed into an emergency operating mode at
this gear ratio level is not critical for the intactness of the
transmission, however, the start-up power, despite excessive
converted torque, may possibly be insufficient for starting to move
the vehicle on slight inclinations after a standstill or a
shut-down motor.
[0010] In order to prevent the transmission from being damaged when
activating the emergency program due to too large a gear ratio or
too small a gear ratio being set for starting to move the vehicle,
valves can be used in which pressure is supplied in proportion to
RPM or speed, e.g. through pitot tubes, however, this is associated
with a considerably increased design complexity. The possible use
of an engine speed program, which supplies information about the
vehicle speed to the hydraulic emergency program, also proves
problematic because such an engine speed program is no longer
available when the electronic control unit, which adjusts the
pressure ratio on the variable speed gear, fails and thus must be
compensated for via a separate electronic control unit at
additional costs.
[0011] The task of the present invention is to make a method and a
device for controlling a drive train of a motor vehicle with an
available continuously variable automatic transmission with which,
in the event of a failure of at least one control unit that selects
the continuously variable automatic transmission and a transition
from normal operation to an emergency operating mode, a gear ratio
is set in the variable speed gear of the continuously variable
automatic transmission which avoids damage to the transmission and,
at the same time, makes sufficient start-up power available.
[0012] To resolve this, the invention provides for the fact that in
the event of failure of the electronic control unit, the frictional
connection between the drive assembly and the continuously variable
automatic transmission is interrupted before an emergency operating
mode is made available through an emergency device by
re-establishing the frictional connection.
[0013] As the device for controlling such a drive train with a
continuously variable automatic transmission, which contains a
variable speed gear, and an emergency valve device, which is
activated upon failure of the electronic control unit, is provided
in the pressure supply line to a clutch arrangement of a
forward/reverse driving unit of the continuously variable automatic
transmission, wherein the valve is switched into a position that
separates the pressurized medium flow to the clutch arrangement, in
the event of failure of the electronic control unit, so as to
interrupt the frictional connection between the drive assembly and
the continuously variable automatic transmission through an
emergency program pressure.
[0014] The invented method and/or the invented device,
respectively, allow the frictional connection in the drive train to
be interrupted upon activation of the hydraulic emergency program,
wherein beneficially independent from the tolerance setting of the
disk valves of the variable speed gear, even an over speed of the
driving motor is prevented when the electronic control unit fails
at extremely high vehicle speed and the emergency device is
activated.
[0015] On the other hand, the invented method and the invented
device allow the frictional connection to be established for a gear
ratio which is within the range of the smallest possible gear ratio
(LOW) when re-starting the motor during the emergency operating
mode, i.e., in a state of the continuously variable automatic
transmission in which no governing speed and no applied pressure
control occurs through the variable speed gear, so that sufficient
start-up power is available and a maximum vehicle speed of well
over 100 km/h is ensured, thus making a relatively large operating
range available.
[0016] Further benefits and beneficial embodiments of the invention
result from the patent claims, the subsequent description and the
drawing. The drawing shows:
[0017] FIG. 1 is a drastically simplified block diagram of a drive
train with an electronically controlled continuously variable
automatic transmission;
[0018] FIG. 2 is a simplified hydraulic diagram of an emergency
device for the continuously variable automatic transmission
pursuant to FIG. 1;
[0019] FIG. 3 is a rough diagrammatic longitudinal section through
a valve of a device, during normal driving operation, for
controlling the continuously variable automatic transmission
pursuant to FIG. 1;
[0020] FIG. 4 is a diagrammatic longitudinal section through the
valve pursuant to FIG. 3 in a state in which this valve stops a
frictional connection in the drive train between the drive assembly
and the continuously variable automatic transmission during the
emergency operating mode pursuant to FIG. 1; and
[0021] FIG. 5 is a diagrammatic longitudinal section through the
valve, pursuant to FIG. 3 and FIG. 4, in a state in which this
valve re-establishes the frictional connection in the drive train
pursuant to FIG. 1 again when starting to move the vehicle after
re-starting the engine during the emergency operating mode.
[0022] FIG. 1 depicts a rough diagram of a drive train of a motor
vehicle with a drive assembly 1 which, in the present example, is
designed as an internal combustion engine which is connected via a
drive shaft 2 to continuously variable automatic transmission 3
which is a belt-wrap transmission or CVT. This continuously
variable automatic transmission contains a hydrodynamic torque
converter 4 which, as usual, consists of a pump wheel 5, a turbine
wheel 6, a stator 7 and a converter bridging clutch, wherein the
turbine wheel 6 and/or the converter bridging clutch are connected
with a transmission input shaft 8. The transmission input shaft 8
drives a forward/reverse driving unit 9, which contains clutches
for forward and reverse driving and transmits the speed of the
transmission input shaft 8 directly to a variable speed gear V with
a drive-side, primary taper disk set 10 and a driven-side,
secondary taper disk set 12. With the help of a belt-wrap device 11
in the form of a chain or a sliding chain belt, the force is
transmitted from the primary taper disk set 10 to the secondary
taper disk set 12. Each taper disk set consists of an axially fixed
and an axially displacable disk. The axially displacable taper disk
of the primary taper disk set is called the primary disk S1 and the
axially displacable taper disk of the secondary taper disk set is
referred to as the secondary disk S2. By simultaneously varying the
axially displacable disks S1, S2, the radius of the belt-wrap
device 11 and thus the gear ratio of the variable speed gear V
changes from the smallest possible, high starting gear ratio LOW to
the largest possible, low gear ratio OVERDRIVE. The secondary taper
disk set 12 is connected with the drive shafts of the vehicle
wheels through a driven shaft 13.
[0023] The continuously variable automatic transmission 3 is
controlled, via electromagnetic positioning elements and hydraulic
valves, by an electronic control unit 15 which in the present
example, represents an electronic control device that can be
connected with an electronic motor control device. The clutches and
brakes are supplied with pressure, in a controlled manner, via
these positioning elements, which are not shown in more detail in
FIG. 1. FIG. 1 also shows, as part of the electronic control device
15, a diagrammatic view of a micro-controller 16, a functional
block for controlling the positioning elements 17 and a diagnosis
functional block 18. The electronic control device 15 communicates
with a control device 14, symbolically indicated in FIG. 1, wherein
it determines an operating point in dependency upon input variables
19, e.g., which can be a signal of a load position of the internal
combustion engine 1, a speed signal of the transmission input
shaft, a speed signal of the driven shaft, or the temperature of
the pressurizing medium, and adjusts the appropriate speed value of
the transmission input shaft or the gear ratio of the automatic
transmission 3.
[0024] When the diagnosis functional block 18, which examines the
input variables 19 for plausibility, detects a serious error,
generally the functional block 17 for control of the positioning
elements is deactivated and an emergency operating mode is
initiated in which no governing speed and no applied pressure
control of the secondary disk S2 occurs.
[0025] This embodiment of a drive train, with internal combustion
engine 1 and a continuously variable automatic transmission 3 with
a variable speed gear V shown in FIG. 1, is known as such and
represents an example of where the invented method and the invented
device can be beneficially applied.
[0026] An emergency device, which is activated in the event of
failure of the electronic control unit and/or the electronic
control device 15, suggests itself as the emergency device, which
is also known as such and is depicted in FIG. 2. As the hydraulic
diagram of this emergency device shows in FIG. 2, a pump 22 is
driven by the internal combustion engine 1 or the pump wheel 5 and
feeds a pressurizing medium from a lubricant reservoir 20, via a
filter 21, into a line 23. This line 23 contains in a first
pressure reduction valve 24, in a branched area 23A, and a second
pressure reduction valve 25, in a branched area 23B, as well as a
branching line 23C, from which, in turn, a branch 23D leads to a
primary valve 38, a branch 23E to a setting space 42 of the
secondary disk S2 and a secondary valve 39 in a branch 23F. The
pressure level of the line 23, for the branches 23A through 23F, is
adjusted through the secondary valve 39, which is designed as a
pressure control valve. The first pressure reduction valve 24
establishes a constant pressure, e.g., of 6 bar, in the line 26.
The second pressure reduction valve 25 also establishes a constant
pressure in the line 32 and its branch 32A. A first pressure
control valve 27 and a second pressure control valve 28 are
connected to the line 26, wherein the pressure in the line 29
and/or 33 can be increased or reduced, in a linear fashion,
depending upon the current values adjusted by the electronic
control device 15 via these electromagnetic pressure control valves
27, 28. A first emergency valve 30 and a second emergency valve 31
are connected to the line 29 and/or its branches 29A and 29B,
wherein the first pressure control valve 27 has a pre-controlling
effect, via the branch 29A and/or the line 29, on the emergency
valves 30, 31. The first emergency valve 30 is connected, via lines
34, 35, with the primary valve 38 which is a pre-controlled
pressure reduction valve. The second emergency valve 31 is
connected, via lines 36, 37, with the secondary valve 39 which is a
pressure control valve for the secondary side with the lines 23
and/or 23A through 23F. In case the pressure level in the line 23
is too high, the secondary valve 39 lowers the pressure level by
feeding additional pressurizing medium, via the line 40, to other
components of the continuously variable automatic transmission. The
primary valve 38 adjusts the pressure level of the setting space 41
of the primary disk S1, via the line 43.
[0027] FIG. 2 depicts the emergency operating mode in which the
pressure control valves 27, 28 are currentless, which causes a
reduced pressure level, e.g., of 0.4 bar, to develop in the line 29
and/or 33 compared to the line 26. Each spring of the two emergency
valves 30, 31 is designed in such a way that the spring force is
larger than the force of this reduced pressure. In this way, the
two emergency valves 30, 31, which each can assume a first position
A and a second position B, are biased into position A. In position
A, the lines 29B and 33 are closed, which creates a valve opening
for the lines 32 and 32A with the lines 34, 36 and applies the
constant pressure level of the second pressure reduction valve 25,
as a pre-control pressure, to the primary valve 38 and the
secondary valve 39. The primary valve 38 and the secondary valve 39
allow a constant pressure ratio to be established in the setting
spaces 41 and/or 42 of the primary disk S1 and secondary disk
S2.
[0028] During normal operation, the two emergency valves 30, 31 are
in position B wherein the lines 34 and/or 36 are venting into the
tank and a valve opening is created from the line 29B with the line
35 as well as a valve opening from the line 33 with the line 37. In
this way, the pressure value set by the first pressure control
valve 27 has a pre-control effect on the primary valve 38 and/or
the pressure value set by the second pressure control valve 28 has
a pre-control effect on the secondary valve 39. While the first
pressure control valve 27 adjusts the gear ratio of the variable
speed gear 6, the second pressure control valve 28 adjusts the
applied pressure of the secondary disk S2.
[0029] FIG. 3 through FIG. 5 show a device, for executing the
method pursuant to the invention, which has a valve 44 that is
arranged in a pressure feed line 45 for the clutch arrangement of
the forward/reverse driving unit 9. This valve 44 is designed in
such a way that in the event of failure of the electronic control
unit and/or of the electronic control device 15, it interrupts the
frictional connection between the internal combustion engine 1 and
the continuously variable automatic transmission 3 and
re-establishes the frictional connection when restarting the
internal combustion engine 1 during failure of the electronic
control device 15 in order to enable an emergency operating mode,
e.g., via the emergency device pursuant to FIG. 2.
[0030] Of course, the invented device in the special embodiment and
hydraulic connection of the valve 44 is also suitable for other
emergency devices, for example, such with only one emergency
valve.
[0031] The valve 44, which serves the purpose of interrupting the
frictional connection in the present embodiment, is arranged in the
pressure supply line 45 to the clutch arrangement of the
forward/reverse driving device 9 in such a way that in the event of
failure of the electronic control unit 15, it is switched, via an
emergency program pressure, into a position that interrupts the
pressurizing medium flow to the clutch arrangement and is switched
into a position that releases the pressurizing medium flow to the
clutch arrangement when re-starting the internal combustion engine
1 during failure of the electronic control device 15.
[0032] From a design point of view, the valve 44 is a two-step
valve with a first valve stem 46 and a second valve stem 47,
wherein the task of the first valve stem 46 consists of assuming a
position that releases or blocks the pressurizing medium supply
line 45 to the clutch arrangement, while the second valve stem 47,
whose working space 48 is connected with the working space 50 of
the first valve stem 46 via a line 49, clearly establishes the
shifting position of the first valve stem 46.
[0033] In the embodiment shown in FIG. 3 through FIG. 5, the first
valve stem 46 is designed with a first piston section 51 and a
second piston section 53, which is separated from the first one by
an area 52 of smaller diameter, wherein an active area 51A of the
first piston section 51, which faces away from the second piston
section 53, acting against the force of a spring 54 limits the
pressurizing medium feed line 45 to the clutch arrangement of the
forward/reverse driving unit 9. In the working space 50 of the
first valve stem, the second piston section 53 limits a chamber 48A
with a connection 55 for the emergency program pressure PNOT
through an effective surface 53A, which is facing away from the
first piston section 51 has a step design. In the open position of
the pressurizing medium line 45, the working space 50 of the second
valve stem 47 joins, via the line 49, with a gap 48B between its
first and second piston sections of the first valve stem 46.
[0034] The second valve stem 47 is designed with a first piston
section 56 and a second piston section 58, which is separated from
the first one through a smaller diameter area 57, wherein an active
area 56A, which faces away from the second piston section 58, of
the first piston section 56 acting against the force of a spring 57
limits a chamber 50A into which the connection 58 for the emergency
program pressure PNOT and the line 49 to the working space 48 of
the first valve stem 46 join which, however, can both be blocked by
the first piston section 56. In the working space 50 of the second
valve stem 47, a smaller effective surface 58A, which is facing
away from the first piston section 56, limits a chamber 50B with a
connection 59 for the main pressure PHD and a magnetic device 60,
which is activated in the emergency program and, in the present
embodiment, is designed as a magnetic switch. A connection 61, for
a pressure control pressure PEDS, joins into a gap 50C between the
piston sections 55, 58.
[0035] The different positions which the valve 44 assumes depends
upon the emergency program pressure PNT, the pressure PKV in the
pressure feed line 45 to a forward clutch of the forward/reverse
driving unit 9, the main pressure PHD and the pressure control
pressure PEDS, are explained in more detail in the following.
[0036] FIG. 3 shows the valve 44 during normal driving operation in
which the first valve stem 46 assumes a first position POSI, in
which it is switched against the pressure PKV in the pressure feed
line 45 to the forward driving clutch and the spring elasticity of
the spring 54 into its position that releases the pressure feed
line 45. Meanwhile, the second valve stem 47 assumes a first
position POSIII in which it blocks the connection 48 for the
emergency program pressure PNOT and the line 49 to the working area
48 of the first valve stem 46 when fed with the main pressure PDH
and the pressure control pressure PEDS.
[0037] In this state, the clutch pressure PKV is applied to the
forward/reverse driving unit, and the frictional connection from
the internal combustion engine 1 to the variable speed gear V of
the continuously variable automatic transmission 3 prevails.
[0038] The position of the valve 44, shown in FIG. 4, is the one it
assumes in the event of failure of the electronic control unit 15.
In this case, an emergency program pressure PNOT, e.g., of 6 bar,
prevails which switches the first valve stem 46 into a second
position POSII in which it is shifted with its first piston section
51 against the clutch pressure PKV in the pressure feed line 45 and
against the force of the spring 54 so that, with its first piston
section 51, it blocks the pressure feed line 45 to the
forward/reverse driving unit 9. At the same time, the first valve
stem 46 blocks, via its second piston section 53, the connection of
the line 49 which leads to the working area 50 of the second valve
stem 47. In the event of failure of the electronic control device
15, the second valve stem 47 remains in its first position POSIII
as long as the main pressure PHD is applied to it, i.e., as long as
the internal combustion engine 1 is running and the pressure supply
is maintained. With an interruption in the pressure feed line 45,
the frictional connection between the internal combustion engine 1
and the variable speed gear V is separated in the state shown in
FIG. 3.
[0039] In this non-frictionally engaged state, the gear ratio in
the variable speed gear V can be adjusted in such a way that with a
subsequent new start of the internal combustion engine 1 and a
continuous failure of the electronic control device 15, a gear
ratio INOT is established which enables sufficient power to start
moving the vehicle and a maximum vehicle speed of at least 100
km/h. It is beneficial when the gear ratio is within the range of
1.0 to 1.6. In the present example, a gear ratio INOT in the range
of 1.3 to 1.6 has been set.
[0040] FIG. 5 depicts a state of starting to move the vehicle in
the emergency program. When the internal combustion engine 1 is
shut off, the main pressure PDH drops to a value approaching zero.
The pressure control pressure PEDS, that is applied to the second
valve stem 47, also decreases. The second valve stem 47 is
attracted by the force of the magnetic switch 60, activated by the
emergency program, which causes the valve stem to assume a second
position POSIV, in which its first piston section 56 opens the
connection 58 for the emergency program pressure PNOT and the
connection to the line 49 which leads to the working area 48 of the
first valve stem 46. In this way, the pressurizing medium, at an
emergency program pressure, reaches the gap 48B of the first valve
stem 46, via the line 49, and pushes it--via an effective area 56B
that is larger than the effective area 53A, to which also the
emergency program pressure is applied and which faces away from the
gap 48B and the first piston section 51--into its first position
POSI, in which the first valve stem 46 opens the pressurizing
medium flow of the clutch pressure PKV in the pressure feed line
45.
[0041] The retaining force, with which the second valve stem 47 is
held in its second position POSIV, is specified by the magnetic
switch 60.
[0042] In this way, the frictional connection between the internal
combustion engine and the variable speed gear V is re-established
via the clutch pressure PKV for the forward clutch of the
forward/reverse driving unit 9.
[0043] During normal driving operation or also upon leaving the
emergency program, the second valve stem 48 can be again separated
from the magnetic switch 60, via the main pressure PDH, and the
pressure control pressure PEDS like a "hydraulic reset" and be
shifted into its first position POSIII.
[0044] Reference Numerals
[0045] 1 Drive Assembly, Internal Combustion Engine
[0046] 2 Drive Shaft
[0047] 3 Continuously Variable Automatic Transmission
[0048] 4 Hydrodynamic Converter with Bridging Clutch
[0049] 5 Pump Wheel
[0050] 6 Turbine Wheel
[0051] 7 Stator
[0052] 8 Transmission Input Shaft
[0053] 9 Forward/Backward Driving Unit
[0054] 10 First Taper Disk Set
[0055] 11 Belt-Wrap Device
[0056] 12 Second Taper Disk Set
[0057] 13 Driven Shaft
[0058] 14 Hydraulic Control Device
[0059] 15 Electronic Control Unit, Electronic Control Device
[0060] 16 Micro-Controller
[0061] 17 Functional Block Control Positioning Elements
[0062] 18 Diagnosis Functional Block
[0063] 19 Input Variables
[0064] 20 Lubricant Reservoir
[0065] 21 Filter
[0066] 22 Pump
[0067] 23 Line
[0068] 23A Line
[0069] 23B Line
[0070] 23C Line
[0071] 23D Line
[0072] 23E Line
[0073] 23F Line
[0074] 24 First Pressure Reduction Valve
[0075] 25 Second Pressure Reduction Valve
[0076] 26 Line
[0077] 27 First Electromagnetic Pressure Control Valve
[0078] 28 Second Electromagnetic Pressure Control Valve
[0079] 29 Line
[0080] 29A Line
[0081] 29B Line
[0082] 30 First Emergency Valve
[0083] 31 Second Emergency Valve
[0084] 32 Line
[0085] 32A Line
[0086] 33 Line
[0087] 34 Line
[0088] 35 Line
[0089] 36 Line
[0090] 37 Line
[0091] 38 Primary Valve
[0092] 39 Secondary Valve
[0093] 40 Line
[0094] 41 Setting Space Primary Disk
[0095] 42 Setting Space Secondary Disk
[0096] 43 Line
[0097] 44 Valve
[0098] 45 Pressure Feed Line
[0099] 46 First Valve Stem
[0100] 47 Second Valve Stem
[0101] 48 Working Area of the First Valve Stem
[0102] 48A Chamber of the Working Area of the First Valve Stem
[0103] 48B Gap
[0104] 49 Line
[0105] 50 Working Area of the Second Valve Stem
[0106] 50A Chamber of the Working Area of the Second Valve Stem
[0107] 50B Chamber of the Working Area of the Second Valve Stem
[0108] 50C Chamber in the Working Area of the Second Valve Stem
[0109] 51 First Piston Section of the First Valve Stem
[0110] 51 A Effective Area
[0111] 52 Area of the First Valve Stem
[0112] 53 Second Piston Section of the First Valve Stem
[0113] 53A Effective Area
[0114] 54 Spring
[0115] 55 Connection for Emergency Program Pressure
[0116] 56 First Piston Section of the Second Valve Stem
[0117] 57 Spring
[0118] 58 Second Piston Section of the Second Valve Stem
[0119] 59 Connection for Main Pressure
[0120] 60 Magnetic Device, Magnetic Switch
[0121] 61 Connection/Pressure Control Pressure
1 PEDS Pressure Control Pressure PDH Main Pressure PKV Pressure
supplied to the Forward/Backward Driving Device PNOT Emergency
Program Pressure POSI First Position of the Valve and the First
Valve Stem POSII Second Position of the Valve and the First Valve
Stem POSIII First Position of the Second Valve Stem POSIV Second
Position of the Second Valve Stem S1 Primary Disk S2 Secondary Disk
V Variable Speed Gear
* * * * *